Double element setback lock



Jan. 20, 1953 J. RABxNow DOUBLE ELEMENT sETBAcx Locx 2 SHEETS-SHEET 1Filed Aug. 3, 1949 Siwa/Wto@ JADDE RAenNnw Jan. 20, 1953 J. RABiNowDOUBLE ELEMENT sETBAcx Loox 2 SHEETS-SHEET 2 Filed Aug. 31 1949gmac/nio@ JADE@ RAEIINUW Patented Jan. 20, 1953 UNITED STATES PATENTOFFICE 2,625,881 DOUBLE ELEMENT SETBACK LOCK Jacob Rabinow,.Washington,D. C., assignor to the United States of America as represented by theSecretary of the Army 1 Claim.

sec. 266) Theinvention described herein may be manufactured and used byor for the Government for governmental purposes without payment to meof. any royalty thereon.

This invention relates to a safety setback lock or release for ordnancedevices and more particularly to a device for arming the fuse of anordnance missile only after a predetermined periodr` of. sustainedacceleration such as occurs, for example, in the disch-arge of a rocket.

In ordnance missiles, which commonly carry explosive charges, it isdesirable that the missiles remain safe or unarmed.until after they havebeen fired. This ensures maximum safety of the using personnel, yetenables the explosive to cause damage to the target. Various means areused to secure this result. For example, rotating missiles may beequipped with arming mechanisms which are responsive to the centrifugalforces developed when the lmissile is fired. Nonrotating missiles, suchas mortar shells, certain classes of rockets, and the like, areordinarily equipped with arming mechanisms which are responsive to theforces of setback, which occur when the missile is launched.

Until very recently, many such arming devices were not shockproof, andthe missile could accidentally be' placed in the armed condition if itwere dropped or otherwise subjected to a strong mechanical shock.

The present invention deals with a particular vspecies of double elementrelease which is respons'ive tov sustained acceleration only, and whichmay be rapidly, easily and cheaply manufactured on screw machines. Whilemy device may be produced in any convenient size, for the purposes ofeconomy of cost and space, and ease of manufacture, I prefer to make thedevice approximately 1A, inch in maximum diameter and approximately linch in length, or smaller.

The specific nature of the invention as well as other objects andadvantages thereof will clearly appear from a description of a preferredembodiment as shown in the accompanying drawing, in which Figure 1 is alongitudinal section of a projectile detonator or fuse nose embodying myinvention.

Figure 2 is a longitudinal section to a greatly enlarged scale of thesetback safety lock shown in Figure l, in its initial or safe condition,

Figure 3 is a sectional view of part of the device shown in Figure 2,showing an initial phase of the action.

Figure 4 is a view similar to Figure 3 showing the final armed positionof the safety lock.

2 Figure 5 is a cross section taken on line 5-5 of Figure 2. y

Figure 6 is a cross section taken on line 6--6 of Figure 4.

Figure 7 is a view similar to Figure 3 showing the action due to anonsustained shock.

Figure l shows an example, for the purpose of illustration, of anorganization employing safety release or lock, which is indicatedgenerally at30. The fuse ZI is adapted to be' screwed into the nose of aprojectile by means ofy threads 22. A transverse bore 23 is closed bythreaded block 24 and contains a plastic slidable element 21, which maybe suitably'keyed to prevent rotation in the bore, this element beingbiased to the right in Figure 1 by spring 25, and restrained againstdisplacement by my safety setback release generally indicated at 30.Part of the release element projects into recess 3i in b0re23 to preventmotion of slidable element 21. It will be apparent that as thisprojection 3l is withdrawn into safety release 30 the slidable element21 will move to the right until detonator 28 is aligned with firing pin33y to arm the fuse in known fashion. Upon impact the detonator will befired by pin 33 which will in turn set. off booster 24 to explode theprojectile charge. It will be understood that in place of the impactmechanism shown any other type of fuse mechanism may be employed. Myinvention is concerned primarily with the safety setback releasemechanism which will be described in more detail below with reference toFigures 2 to 7.

In each of these. figures, I` isa weight which is free to move in onedirection'insidea second weight or latch 2. Weight I is forwardlypressed by spring 4, and is retained in weight 2 by a lip 2a formedthereupon. Weight 2 is free to move in one direction in sleeve 3, and isretained therein by lip 3a which is formed thereupon and bears uponshoulder 2b formed in weight 2. Weight 2 is forwardly pressed in sleeve3 by spring 5. Ball 6, when the device is in the unarmed position,Figure 1, rests with slightly more than half its diameter in hole 2c ofweight 2, and slightly less than half its diameter in hole 3b of sleeve3, locking weight 2 to sleeve 3. The diameter of hole 3b is slightlyless than the maximum diameter of ball 6; this prevents ball 6 frompassing through hole 3b and becoming disassembled from the device Whilethe `device is' in the unarmed position of Figure l.

When setback occurs, as when the missile is fired, weight I, responsivethereto, moves rear- Wardly against the force of spring 4. This motioncauses the constricted portion la of weight I to be brought intojuxtaposition with ball 6, which is thus freed to move inwardly and isurged to do so bythe contour of hole 2c.

If themissile has been accidentally dropped, as against a hard surface,the setback force is only momentary, and the sloped shoulder I b ofweight I returns ball 6 to its original position, locking sleeve 3 andweight 2, when weight I is forwardly pressed by spring 4.

1f, however, the missile vhas been launched, setback force is sustained,and the action hereinafter described occurs in place of the actiondescribed in the paragraph immediately preceding.

Weight 2, responsive to the continued force of setback and freed fromsleeve 3 by the inward motion of ball 6, moves rearwardlyagainst thepressure of spring 5, carrying ball B with it as shown in Figure 3. Ifthe setback is sufficiently sustained, the slope of hole 2c causes ball6to move outwardly into hole 3c because of setback force on ball 6. Whensetback has ceased, springs 4 and 5 tend to return weights I and 2,respectively, to their original positions. Sloping shoulder Ib of weightI, is used to urge ball outwardly so that it occupies a position withslightly more than half its diameter in hole 2c of weight 2 and slightlyless than half its diameter in hole 3c of sleeve 3 if it has failed toenter this position due to the force of setback. Thus ball 6 locksweight 2 in the retracted position in regard to sleeve 3, as shown inFigure 4.

At the end of setback, the device is thus in the condition shown inFigure 4. Weight l has assumed its original position in respect toweight 2. Weight 2 has moved and is locked rearwardly with respect tosleeve 3. Consequently both weight I and weight 2 are contained withinsleeve 3.

In some applic-ations, it is desirable that Weight 2 be expelled fromsleeve 3 after the cessation of setback forces. In this condition, lip3a is omitted from sleeve 3, and shoulder 2b may be omitted from weight2. Ball 6 may then roll outwardly from weight 2 and sleeve 3, so thatspring 4 expels weight 2 from sleeve 3 when setback has ceased.

When the device is used to block motion of a powder train interrupter orsimilar mechanism such mechanism is blocked by the forward portion ofweight 2, and is not free to move to its armed position until the actiondescribed has taken place as shown in Figure 1, and the device hasassumed the position shown in Figure 2.

I claim:

'I'he combination with a fuse for ordnance missiles of means forming anaxial bore in said fuse, a firing pin positioned within said bore, meansforming a transverse bore within said fuse, a plastic element slidablewithin said transverse bore and adapted to accommodate a detonator,resilient means adapted to bias said plastic element into normal armedposition to align said ring pin with said detonator, means forming alongitudinal bore in said plastic element, safety set back releasemechanism within said latter bore to compress said resilient means forlatching said plastic element intounarmed position, said safety setVback release mechanism comprising, a rst -cylinder stationary withinsaid latter bore, a second cylinder slidable within said first cylinderand spring biased forwardly to extend in a forward direction asubstantial distance from the forward end of said first cylinder, meansto latch said rst and second cylinders together to prevent axialmovement, a third cylindrical Weight slidable within said secondcylinder and spring biased in a forward direction to place the forwardend of said weight in substantial alignment with the forward end of saidsecond cylinder, slot means in said fuse for accommodating the forwardlyextending portions of said second cylinder and said Weight, said Weightbeing constructed and arranged upon sustained set back to release saidmeans latching said first and second cylinders whereby said secondcylinder is forced rearwardly and out of said slot means by sustainedset back due to launching acceleration to release said plastic elementand to enable said resilient means to move said element into armedposition.

JACOB RABINOVV.A

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,549,763 Greenwell Aug. 18, 19251,690,331 Brayton Nov. 6, 1928 FOREIGN PATENTS Number Country Date558,570 Great Britain Jan. 11, 1944 690,879 France June 30, 1930

